1. Field of the Invention
This invention is directed to magnetic bubble domain devices or systems, in general, and to improved systems with period stretching devices, in particular.
2. Prior Art
In the present state of the art magnetic bubble domain systems, major tracks serve to propagate the bubbles to and from the input and output ports of the system in basically the same propagation elements as those in the storage loops. That is, the basic propagation elements all have the same general size, shape and operating characteristics. The basic propagation elements in the minor loops are designed for maximum storage density and to provide adequate bias margin for reliable propagation. The use of these same propagation elements in major tracks, such as input/output tracks or the like requires that the spacing between switches on the major track be at least equivalent to two bits (or periods) in length. That is, because of the geometry of the storage loops, the switches are spaced along the major track by the appropriate distance. As a result, each output track can handle only alternate bit streams from the storage loops. Therefore, in order to bring the data rate of the magnetic bubble domain system up to the operating speed or data rate of the intrinsic field rate, a pair of input/output (major) tracks are used to handle each of the input/output functions. This type of organization is known in the art as the "split field" or "ping-pong" scheme. In either of these known schemes, the two output tracks either merge together into one detector or each delivers a bubble to a separate detector. The first mentioned approach increases the length of the major tracks by about fifty percent which adds to the access time in retrieving information from storage. The second approach increases the lead count on the magnetic bubble domain and requires more electronic circuitry and, thus, adds to the cost of the module. Each of these above known techniques also adds to complexity and, therefore, reduces reliability of the chip.